Return rail key assembly for stokers



June 2,1942. R. HAMILTON 2,284,864

RETURN RAIL KEY ASSEMBLY FOR STOKERS June 2, 19,42. R. HAMILTON RETURN RAIL KEY ASSEMBLY FR STOKERS Filed Dec. 2, 1939 2 Sheets-Sheet 2 INVENTOR Patented June 2, 1942 'RETURN 1min KEY ASSEMBLY Fon sroknns Robert Hamilton, Closter, N. J., assigner to Comp bustion Engineering Company, Inc., New York, N. Y.

Application December 2, 1939, Serial o.`307,213

9 Claims.

The present invention relates to travelling grate stokers and particularly to an improved form of return rail key therefor.

The fuel supporting surface of a travelling grate stoker due to its nature takes the form of an endless conveyor made up of a plurality of grate bars .or keys mounted in end'to end and and illustrates the manner of removal of areturn rail key assembly; and

Fig. 6 is a sectional view. on line 6-#6 in Fig. 1 illustrating themanner of securing ordinary grate keys to a carrier bar.

As illustrated in Fig. 1, a travelling grate of Y the type contemplated herein is made up of a side by side relation on carrier bars extending transversely of the stoker, the carrier bars being connected at their ends, and sometimes at intermediate points also, to driving chains running over sprockets at the front and rear of the st-oker for advancing `the fuel supporting surface through the furnace. known as return rail keys because they act to support the lower reachV of the conveyor-like grate on its return from the rear endV to the front end of the Stoker as these keys ride upon and are in turn supported by the return rails. Due to the surface wear `which these keys suffer in being dragged along the return rails under the weight of the grate, provision must be' made for their removal and replacement, preferably without dis- Some of these keys are* turbing any of the remaining keys of the grate.

A feature of the invention resides in anl improved form of return rail key assembly permitting the ready removal of any worn return rail key without ldisturbing any of the other keys forming part of the travelling grate.

A second feature resides in an improved construction and arrangement enabling removal of any ordinary grate key from its carrier bar without rst removing all other keys between its location and one end of the carrier bar.

The invention will be best understood upon consideration of the following detailed description of an illustrative embodiment thereof when read in conjunction with the accompanying- Figure l is a fragmentary plan view of the fuel Figure 3 is a plan view corresponding to Fig. 2.,

partly broken away, to illustrate details of con`V struction; l

, Figure Il is a rear end view of the return rail key assembly shown in Figs. 2 and 3;

Figure 5 is a fragmentary elevation of the stOke'r, partly in section, as seen at the location ofthe driving sprockets which advance the gratev plurality of grate keys I arranged in side by Y side and end to end relation on carrier bars i I that extend transversely of the grate. Secured upon each carrier bar II near its forward longiu tudinal face isa dovetail member I2 seating in corresponding dovetail recesses on the undersides of the grate keys Il) to secure themto thecarrier bar. As illustrated in Fig. 6 the dovetail' recess that secures an ordinary grate key Ill to the dovetail member I2 of a carrier bar Itis formed by oppositely facing hooked-like lugs I5 depending from the key I0. The hooks I5 engaging beneath the dovetail shoulders of carrier bar II prevent a key Il) being lifted off until slid along the bar to aA position where one hook I5 alines withone of several slots El cut, vertically in the rear longitudinal face of the dovetail portion I2 of the bar II, Fig. 1. These positions are ordinarily occupied by the special keys, designated as a whole by the numeral I3 in Fig. l, that are mounted at intervals transversely of the carrierbar between adjacent grate keys 'I and function as return rail keys, as well as to lock the standard keys I0 against removal. As the lower reach of the endless conveyorlike grate travels from the rear back to the front of the" stoker the key assemblies i3 ride upon return rails hl located beneath the grate, as shown in Fig. 5, so that the lower reach of the grate is supported to prevent its sagging.

In accordance with the present invention each return rail ke'y assembly I3 consists of three major parts, a pair of keys 2i) and 2l positioned side by side and a locking member 22 mounted between and pivotally connectedY tothem. |'he opposing faces of the keys 2U and 2| are maintained spaced by bosses 23 thereon so that the locking member 22 may be mounted therebetween in a position overlying avslot lll in carrier bar II, the keys 2l), 2l, themselves being pushed immediately adjacent to and straddling 'the slot. Rivets 2f4 extending through the bosses rigidly connect these keys.

The locking member 2-2` is provided nearY its forward end with laterally lprojecting trunnions 25 engagedin recesses 2li4 in the opposing side open at theirl forward ends for a reason which will be referred to hereinafter.

Depending from the underside of each key 20 and 2| near its forward end is a hook member 21 which is a portion of the forward boss 23 and is engaged with the undercut shoulder 2B on the forward longitudinal face of the dovetail member I2 on which the grate keys III are mounted. Near their rear ends the keys 23 and 2| have lugs 31| which are portions of the rearward boxes 23 and depend therefrom into the usual air passage 3| in carrier bar II. Lugs 3i] are connected to an angle member or hook 32 engaged beneath the underside of the longitudinal rib 33 that defines the rear edge of the air passage 3|. Only a single hook member 32 is required for the two keys Z and 2|. The angle member 32 is connected tothe lugs 39 by rivets 34 and thus serves also to rigidly connect the keys 20, 2| at their rear portions.

The hooks 21 and 32 on the keys 20 and 2| act to prevent lifting of a return rail key assembly I3 from the carrier bar II until the assembly is moved laterally of the bar, to the right in Fig, 2, for disengaging the hooks. tion shown in Fig. 2 this lateral movement of the return rail key assembly is prevented by a lug 33 on locking member 22 which is positioned to nt into a slot 4!! and engages a vertical portion 31 of the carrier bar II that faces in the direction A.

opposite to the direction of lateral movement for disengaging the return rail key assembly. In the construction illustrated this vertical face 31 is provided by notching the undercut shoulder 38 at the rear longitudinal face of dove-tail member I2 so as to form the vertical slot di! in Fig. 1. A cotter pin 38 engaged in transverse apertures near the rear end of the locking member 22 and the key 2| prevents the locking member being pivotally raised until the cotter pin is removed. As shown in Figs. 3 and 4, particularly, the ends of cotter pin 38 are concealed within recesses 39 in the outer faces ofl key 2| and locking member 22. Thus the cotter pins are shielded by overhanging parts of these elements and protected against burning.

As illustrated at the top right portion of Fig. 5, the forward end or nose of each key ordinarily overlaps the rear or tail end of th next key in advance as is customary. Accordingly, a return rail key assembly cannot be removed nor its locking members 22 raised until the assembly is located at a point where it is passing around the chain sprockets. When the tail end of the return rail key which it is desired to remove is canted sufficiently to clear the nose of the next succeeding key and cotter pin 33 is removed, the locking member 22 may be raised. When the lug 35 has been lifted out of slot ID and clears the top of the dovetail member I2 the return rail key assembly I3 may be shifted laterally of its carrier bar II, i e. forwardly of the grate, to a position in which the hooks 21 and 32 clear the shoulder portions of the bar that they engage. The entire assembly may then be lifted off the carrier bar.

If only a locking member 22 requires replacement it may be readily removed when the cotter pin is taken out. The only other direct connection between the keys 20, 2| and the locking member 22 consist of the trunnions 25 on the latter seating in the recesses 26 in the keys. Because these recesses are open at their forward ends to the front end face of the keys, the trunnions may readily be slid out of the recesses to detach a locking member 22.

When in the posi- L In the event that a grate key IU becomes worn and requires replacement removal of the nearest return rail key assembly I3 permits the grate keys being slid along the carrier bar II to the location of the cut-away portion or slot 40 in the dove-tailed member I2. On reaching this position each grate key may be tilted upwardly and forwardly and then lifted off the carrier bar because the provision of the slot 40 renders the dove-tail I2 incomplete at this point.

What I claim is:

1. In a chain grate stoker; a transversely extending carrier bar having a vertical slot cut in one of its longitudinal faces at a point between its ends; grate keys mounted on said bar beyond said slot; oppcsitely facing hooks depending from said keys and engaged beneath said bar for securing them thereon, each key being slidable along said bar to aline one hook thereof with said slot to permit lifting and removal of the key from the bar; another key mounted on said bar immediately adjacent the slot therein; hooks on said other key engaged beneath the said bar to prevent lifting of the key from said bar, said key being movable laterally of said bar to disengage its hooks to permit said lifting; a locking member carried by said other key and engaging a face portion of said bar facing in the direction opposite said lateral movement to remove said key for locking said key on said bar; and a pivotal connection between said locking member and said other key for permitting the latter to be disengaged from said bar to enable removal of said other key from the path of said grate keys to positions in which one hook thereof alines with said slot.

2. In a chain grate stoker; a transversely extending carrier bar having a vertical slot cut in one of its longitudinal faces at a point between its ends; grate keys mounted on said bar beyond said slot; oppositely facing hooks depending from said keys and engaged beneath said bar for securing them thereon, each key being slidable along said bar to aline one hook thereof with said slot to permit lifting and removal of the key from the bar; another key mounted on said bar immediately adjacent the slot therein; hooks on said other key engaged beneath said bar to prevent lifting of the key from said bar, said key being movable laterally of said bar to disengage its hooks to permit said lifting; a locking member carried by said other key and having a lug depending into the slot in said bar to engage a face portion of said bar facing in the direction opposite to that of the lateral movement of said other key for preventing said movement; and a pivotal connection between said locking member and said other key for permitting said lug to be raised from said slot to enable removal of said other key from the path of said grate keys to positions in Which one hook thereof alines with said slot.

3. In a travelling grate stoker; a transversely extending carrier bar; a pair of spaced grate keys mounted side by side on said bar and having alined recesses formed in the opposing side faces thereof, said recesses being open at the under side of said keys; depending hooks on said keys engaged beneath said bar to prevent lifting of the keys from said bar, said keys being movable laterally of said bar for disengaging said hooks; a locking member mounted between said keys and engaging a portion of said bar facing in the direction opposite said lateral movement for preventing it; and trunnions on said locking member seated in said key recesses for permitting pivotal movement of `said member with respect to said keys to disengages said locking member from said bar and to swing itto a position wherein said trunnions may be disengaged from the recesses in said keys for enabling dismounting of said locking member from between said grate keys without removing them from said carrier bar.

4.V In a travelling grate Stoker.; a transversely extending carrier bar having a vertical slot cut in l said keys; depending hooks on said keys engaged beneath said bar to preventv lifting of the keys `from said bar, said keys being movable laterally of said bar for disengaging said hooks; a locking member mounted between said keys and having a lug depending into said slot for engaging a face portion of said bar facing in the direction opposite said lateral movement for preventing said movement; and trunnions on said locking member seated in said key recesses for permitting pivotal movement' of said member with respect to said keys to disengage said locking lug from said bar and to swing said member to a position wherein said trunnions may be disengaged from the `recesses in said keys for enabling dismounting of said locking member from betweensaid grate keys without removing them from said carrier bar. v

5. In a travelling grate having a transversely extending carrier bar; a grate key mounted onV said bar having depending .hook portions facing in the same direction and engaged beneath the bar to prevent lifting of the key from the bar,

said key being movable laterally of the bar to` disengage saidhocks and permit said lifting; a locking member carried by said key and having a portion engaging a part of said bar facing oppositely to the direction of lateral movement of said key to disengage it for preventing said movement of said key; and a pivotal connection between said key and locking member for permit- .l

ting the latter to be disengaged from said bar to allow said lateral movement of said key.

6. In a travelling grate; a transversely extending carrier bar having an opening therethrough intermediate its, longitudinal edges; a grate key mounted on said bar; similarly facing hooks depending from said key, one hook engaging beneatha lower longitudinal edge of said bar and the other depending through said opening to engage the under side of said bar at one side of said opening; said key being movable laterally of the bar to disengage said hooks and permit lifting of the key from the bar; a locking member carried by said keyrand having a portion engaging a face of said bar facing to oppositely said direc-V tion of lateral movement to prevent said movement of said key; and a pivotalV connection between said keyl and locking member for permitv ting the latter to be disengaged from said bar to allow said lateral movement of said key.

7. In a travelling grate having a transversely extending carrier bar; a grate lkey mounted on said bar and having similarly facing hooks depending from said key and engaged beneath the bar to prevent lifting of the key from the bar,

said key being movable laterally of the bar to disengage said hooks and permit said lifting;` a locking member carried by said key and engaging a portion of said bar facing oppositely to said direction of lateral movement to prevent said movement of said key; a pivotal connection between said key and locking member for permitting the latter to be disengaged from said bar to allow said lateral movement of said key; and means securing said locking member in locking relation with said key.

8. In a travelling grate having a transversely extending carrier bar; a grate key mounted on said bar; rearwardly facing hooks ldepending from said key and engaged beneath the bar to prevent lifting of the key from the bar, said key being movable forwardly on the b-ar to disengage said hooks and permit said lifting; and a locking member carried by said key and having a portion v engaging a rearwardly'facing portion of said bar to prevent said forward movement of said key; and a pivotal connection between said keyy and locking member for permitting the latter to be disengaged from said bar to allow said lateral movement of said key. I

9. In a travelling grate wherein grate key assemblies constructed as recited in claim 6 are mounted so'that `the tail portion of one grate key assembly is overlapped by the nose portion of the succeeding grate key assembly, characterized'in that in eachv grate key assembly the key and locking member are positioned in side by side relation with aligned transverse apertures extending therethrough with the aperture of each member extending through a recess in the outer side face thereof, said apertures being located in the tail portion of the key and locking member so as'to be overlapped by the nose portion of the following key; and fastening means extending .through said apertures and located entirely within the apertures in the recesses and key in the locking member'.

ROBERT HAMILTON. 

